Until recently, diverse opinions were held concerning the factors that control the blood supply of the brain. Experimental findings of one observer were inconsistent with those of another, and clinical observations could be explained by neither. Textbooks of physiology still reflect this unsatisfactory state of affairs. During the past five years, however, investigators in a dozen laboratories have obtained results which for the first time agree on major points. A review of most of this work, together with some of the original articles, may be found in the volume entitled "The Circulation of the Brain and Spinal Cord," published by the Association for Research in Nervous and Mental Disease.1 To this may be added several references.2 It seems worth while to piece together the recent findings and to examine the resulting pattern. Any such attempt at synthesis unavoidably reflects the author's personal views.
After review of the evidence,